Lake Peipus is a remnant of a body of water which existed in this area during an Ice Age. It covers 3,555 km2, and has an average depth of 7.1 m, the deepest point being 15 m.[3][4] The lake has several islands and consists of 3 parts:

The lake is used for fishing and recreation, but suffered from some environmental degradation from Soviet era agriculture. Some 30 rivers and streams discharge into Lake Peipus. The largest rivers are the Emajõgi and the Velikaya River. The lake is drained by the Narva River.

The lake is a remnant of a larger body of water which existed in this area during an Ice Age.[5] In the Paleozoic Era, 300–400 million years ago, the entire territory of the modern Gulf of Finland was covered by a sea. Its modern relief was formed as a result of glacier activities, the last of which, the Weichselian glaciation, ended about 12,000 years ago.

The banks of Lake Peipus have smooth contours and form only one large bay – Raskopelsky Bay. The low shores of the lake mostly consist of peat and are bordered by vast lowland and marshes which are flooded in the Spring with the flooding area reaching up to 1000 km2.[6] There are sand dunes and hills, covered with pine forests. Along the sandy shores there is a 200–300 m wide stretch of shallow waters.[7]

The relief of the bottom is uniform and flat, gradually rising near the shores and covered with silt, and in some places with sand.[8] The deepest point of 15.3 m is located in the Teploe Lake, 300 m from the coast.[9]

The lake is well-flowing, with the annual inflow of water equal to about half of the total water volume.[6]

The lake water is fresh, with a low transparency of about 2.5 m due to plankton and suspended sediments caused by the river flow.[6] Water currents are weak (5–9 cm/s); they are induced by the wind and stop when it ceases. However, during the spring flood, there is a constant surface current from north to south.[8]

Because of the shallow depth, the lake quickly warms up and cools down. Water temperature reaches 25–26 °C in July.[9] The lakes freeze in late November – early December and thaws in late April – early May, first lakes Teploe and Pihkva and then lake Peipus.[6]

About 30 rivers flow into the lake.[10] The largest are Velikaya and Emajõgi, smaller rivers include Zadubka, Cherma, Gdovka, Kuna, Torohovka, Remda, Rovya, Chernaya, Lipenka, Startseva, Borovka, Abija, Obdeh, Piusa, Võhandu, Kodza, Kargaya, Omedu, Tagajõgi and Alajõgi. The lake is drained by only one river, the Narva into the Baltic Sea.[3]

The lake contains 29 islands with a total area of 25.8 km2, with 40 more islands located within the delta of the Velikaya River.[9] The islands are low wetlands, elevated above the lake surface on average by only 1–2 m (maximum 4.5 m) and therefore suffer from floods. The largest islands are Piirissaar (area 7.39 km2, located in the southern part of Lake Peipus), Kolpino (area 11 km2, in the Pihkva Lake) and Kamenka (area 6 km2). In the center of Pihkva Lake there is a group of Talabski Islands (Belova, Zalita and Talavenets).[6]

The ecological condition of the lake basin is, in general, satisfactory – water is mostly of grades I and II (clean), and is of grade III in some rivers due to the high content of phosphorus. The water condition of the rivers has improved since 2001–2007, but there is an increase in population of blue-green algae. The main problem of Lake Peipus is its eutrophication.[13]

The towns standing on the banks are relatively small and include Mustvee (population 1,610), Kallaste (population 1,260) and Gdov (population 4,400). The largest city, Pskov (population 202,000) stands on the Velikaya River, 10 km from the lake.[7] Ship navigation is well developed and serves fishery, transport of goods and passengers and tourist tours.[12][14][15] The picturesque shores of the lake are a popular destination for tourism and recreation at several tourist camps and sanatoriums.[16][17][18]

The largest city on the lake, Pskov, is also one of the oldest cities in Russia, known from at least 903 AD from a record in the Primary Chronicle of the Laurentian Codex.[21][22] Several historical buildings remain in the city, including Mirozhsky Monastery (1156, which contains famous frescoes of 14–17th centuries), Pskov Kremlin (14–17th centuries) with the five-domed Trinity Cathedral (1682–1699), churches of Ivanovo (until 1243), Snetogorsky monastery (13th century), Church of Basil (1413), Church of Cosmas and Damian (1462), Church of St. George (1494) and others.[23]